CIHM 

Microfiche 

Series 

(Mlonographs) 


iCMH 

Collection  de 

microfiches 

(monographles) 


Technical  and  Bibliographic  Notes  /  Notes  techniques  et  bibliographiques 


Th«  InstHut*  hat  atttmpltd  to  obtain  th«  bttt  original 

cow  avaHable  for  filming.  Features  of  this  copy  which 
may  be  bibliographically  unique,  which  may  aRer  any  of 
the  images  in  tha  reproduction,  or  which  may 
significantly  changa  the  utual  mtttwd  of  fflming  ara 
chedced  below. 

□ Coloured  covers  / 
Couveiture  de  couleur 

□ Covers  damaged  / 
Couverture  endommagie 

□ Covers  restored  and/or  laminated  / 
Couveiture  restaur^e  et/ou  pelliculie 

I  Cover  title  missing /lje  ttre  de  couveitwe  manque 


 I  Cotourad maps/ Cartas giegrapNquat an eodmr 

□ Coloured  ink  (i.e.  other  than  blue  or  black)  /* 
Encre  da  couiaur  (i.*.  atiba  qua  blaue  ou  noira) 

□ Cotoured  plates  and/or  illustratk>ns  / 
PItnchas  atfou  ikistratfona  an  coulaur 

□ Bound  with  other  material  / 
Rell«  avee  d'autraa  docwnaMs 

□ Only  edition  available  / 
SeulaMMondiaponMa 

□ light  Unding  may  cause  shadows  or  distortk>n  along 
Interior  margin  /  La  reikire  serr^e  peut  causw  da 
rombre  ou  da  la  tfMnion  la  ioi^  da  la  marga 
int^rieure. 

□ Blank  leaves  added  during  restorations  may  appear 
within  the  text.  Whenever  possible,  these  have  been 
omMadftom  filming  /  Use  peut  que  certaines  pages 
blanches  ajout^es  iors  d'une  restauration 
spparaissent  dans  ie  texte.  mais.  torsque  cela  itait 
posaiMa.  eat  pagaa      pas  M  fftniaa. 

0 Additional  comments/  Peginetlon  ia 

CommamalraasuppMmanlaiias:  pagination 


L'instRut  a  mierofUmi  Ie  meilleur  exemplaire  qu'il  lui  a 
M  possibia  de  se  procurer.  Les  details  da  cat  exem- 
plaire qui  soni  peut-«tre  unk)ues  du  point  da  vua  bibR- 
ographkpe.  qui  peuvent  nwdKler  une  image  reproduile. 
ou  qui  peuvent  exiger  une  modificatkm  dans  la  mllho- 
de  normale  de  filmage  sont  indk)u<s  ci-dessous. 

I    [  Coloured  pagas/Pagas  da  couiaur 

[71  Pages  damagad/P»oaaandofwnag4as 

□ Pages  restored  and/or  laminated  / 
Pages  rastaurlaa  aUMi  paiReuliaa 

Pages  discotoured,  stained  or  foxed  / 
Paget  d<eoloiiat,taehatefv  p-j^jin 

I    I  Pages  detached/ Pages  cf^t:.  ' J 

I    I  Showthrough/Tiansparencci 

□ Quality  of  print  varies  / 
Quaia*  inigaia  de  rimpresskm 

□ includes  supplementary  material  / 
Con^and  du  materiel  si^^mentaire 

□ Pages  wholly  or  partially  obscured  by  errata  slips, 
tissues,  etc.,  have  been  refilmed  to  ensure  the  best 
possible  Image  /  Les  pages  totatamant  ou 
partiellement  obscurcies  par  un  feuillet  d'errata,  une 
pehire,  etc..  ont  M  film^es  k  nouveau  de  fa(on  k 
obtenir  la  maiaura  image  posiribla. 

□ Opposing  pages  with  varying  colouration  or 
dIseoiouratkNW  ara  flbned  iwfea  10  antura  ttw  batt 
possible  image  /  Les  pages  s'opposant  ayant  des 
colorations  variables  ou  des  d^cotoratlons  sont 
likn<as  deux  fois  afin  tfoManir  la  maMaura  hnaga 


follovs:  p.  199-200. 
coBM  suit:  p.  199-200. 


tOx 


14x  18x  22x  26x  30x 

I   I  I  I  i  I  1  I  I  I  1-/1  I  I  ITTl 

Ifx  20x  24x  aix 


12s 


92x 


Th«  copy  filmed  h«r«  hM  bMn  raprwIiiMrf  ttinln 
to  th«  flMMTOWty  of: 

University  of  Toronto 

Gerstein  Sciences  Information  Centre 

Th«  imagM  appMring  hara  ara  tha  bast  quality 
pesaibia  conaMaring  tha  condition  and  lagibillty 
of  tho  orltliiol  eopv  oftd  in  hooping  wMi  tiw 


Origifiol  eoploa  In  printod  popor  oovors  aro  Mmod 
bag  Inning  wiiti  tfia  front  oow  and  anding  on 
tha  last  paga  with  a  printod  or  Hluatratod  Impraa 
•ion.  or  tha  back  eovor  whan  approprlata.  All 
othar  original  copiaa  ara  fllmad  boginning  on  tha 
first  paga  with  a  printad  or  Hluatratod  Imprao- 
alon.  and  onding  on  tho  loot  pofo  wMi  o  printod 
or  WiMtfscod  improoalont 


Tho  laat  racordad  frama  on  aach  microflcho 
shall  contain  tha  symbol       (mooning  "CON- 
TINUED"!, or  tho  symbol  ▼  (mooning  "iNO"). 
whiolMvor  oppMoOa 

IMopo.  platao.  charts,  ate.,  moy  bo  fiimod  ot 
diffarom  raduetien  ratios.  Thoaa  too  iorgo  to  ba 
antiraiy  includad  in  ona  axposura  ara  fllmad 
beginning  in  tha  uppar  laft  hand  eomor,  loft  to 
right  and  top  to  bonom,  as  many  frames  as 
raquirad.  Tha  following  diagrams  iUuatrata  tho 
inotliods 


L'M«mplair«  film*  fut  wprodyh  sriM  A  to 


University  of  Toronto 

Gerstein  Sciences  Information  Centre 

Lm  imagM  suivantM  ont  *t*  reproduitM  avac  la 
plus  grand  soin.  compta  tanu  da  la  condition  at 
da  to  nattat*  da  raaampto^  film*,  at  an 


Ua  aiiamptolraa  ariginaua  dont  to  aoiraartwra  an 
papiar  aat  iniprinida  aont  fHmda  an  eomman^ant 
par  to  pramiar  ptot  at  an  tarminant  soit  par  la 
darniira  paga  qui  comporta  una  amprainta 
d'impraasion  ou  d'llluatratiMi.  soit  par  la  sacond 
ptot.  aaton  to  eas.  Toua  toa  awtraa  aaamptoiraa 
Oflginauii  sont  fHmda  an  eowwianyant  par  to 
pfaniMva  paga  quI  aonipwta  tma  ampraints 
d'impraasion  ou  d'illustration  at  an  tarminpm  par 
to  damtora  paga  qui  eomparta  una  taito 


Un  daa  symbolas  suivants  apparaitra  sur  la 
damiira  imaga  da  ehaqua  micrefieha.  salon  la 
eaa:  to  aymboto       signifto  "A  tUIVRI".  to 
vynNMia  ▼  atgnma  rf  iv  • 


Laa  canaa.  ptonchaa.  tabtoaux.  ate.,  pauvant  *tra 
fltomte  A  rfaa  tMiM  da  rMuatton  dtftArants 
Lorsqua  to  documant  ast  trap  grand  pour  itra 
raproduit  an  un  saul  cliche,  il  ast  film*  A  partir 
da  i'angto  supAriaur  gaucha,  da  gaucha  i  droita. 
•t  da  haut  an  baa.  an  pranant  to  nombra 
tflmataa  nteaaatira.  Laa  dtoypmmaa  anivbnta 


1 


2 


3 


3 


6 


J) 


Rrprtnted  (or  privutc  <  in  nl,itii>n  irom 
The  AsT«OMiV!»K'Al  Joi-BNAt,  \     XI. MI,  Ni>.  s.  M'"' 


1-0 


DESIR.\BILITY  OF  OBSERVATIONS  OF  THE  SOLAR 
ROTATION  AT  THE  I  IMI  S  OF  ECI.IPSK 

Tn  th''  lini'-^  <>l'  --pt'itrii  from  the  solar  limi)  tluTc  lilt  iiilini;  of 
such  nature  as  to  alft'it  the  mcusurfments  of  tht-  velocity  of  tlio 
sun's  rotation  from  the  displacements  of  these  h'nes.  The  mapni- 
tude  of  till-  olTi'it  varies  from  line  to  line,  \  arious  fa(tor>  eon- 
tribute  to  the  blendinR  oi  spectra."  The  factors  oiu  ratinj;  l)etween 
the  moon  and  the  point  of  ohser\-ation  arc  nearl\  eliminated  just 
before  and  after  totality,  when  only  the  limb  under  observation 
is  visible.  To  inv(  stijiate  the  problem  a  i)o\verful  sju'i  troseope 
(proilucinj;  .spectra  of  scale  alK)Ut  i  mm  to  i  .\)  is  necessary  an<l 
a  large  image  of  the  sun  preferred.  The  region  of  the  ft-group  is 
su^>;este(l  because  the  effect  of  liKmlini;  is  known  for  the  /'  lines 
and  others  near  them,  and  because  iodine  and  chlorine  conii>ari>on 
spectra  are  available.  It  is  ver>'  desirable  that  such  observations 
be  made  at  the  eclipse  of  June  S,  so  that  terrestrial  souri  tsof  lilended 
spi'ctra  may  be  removed  in  order  to  investigate  the  s»>lar  and  inter- 
planetary sources.  The  observations  need  not  interfere  with  those 
during  the  precious  seconds  of  totality. 

At  least  one  ])art\-  is  ])lanninj;'  to  make  ileterminat ions  of  tlic 
speed  of  rotation  of  the  corona  from  displacements  of  the  coronal 
lines  at  the  time  of  total  eclipse  on  June  8.  In  view  of  the  fact 
that  Deslandres.  ("ami)bell.  and  Bosler  haxc  obtained  \ahu-  of 
this  speed  of  from  ,^  to  4  km  j>er  second,  it  is  very  imjMjrtanl  that 
every  precaution  be  taken  to  keep  check  on  the  errors  that  beset 
such  measurements,  in  this  regard  I  would  suggest  that  the  si>ec- 
troscope  be  used  to  determine  the  \ilocit\-  of  rotation  of  the 
re\ersini;  laver  by  observations  of  the  last  and  west  limbs  of  the 


■  Journal  •■>'  Ihr  Royai  .1  \lro>iomii  ,tl  Sm       ni  i  lo,  Joi 

iqi6;  Astrophysiittl  Joiirmtl,  44,  177 -i.Sg,  ami        i<)<),  n>i6. 
•K<lwin  B.  Frost,  Popular  AslroHomy,  a6,  no,  iqiS. 


Ml),  ^inil  .t4i  45 7 1 


300 


MFSOR  COSTKIBl'TfOSS  ASD  NOTES 


sun  before  and  after  totality  of  eclipse,  using  a  comparison  sjH-c- 
trum  and  empioyinK  precisely  the  same  ntethoti  in  determining 
the  velocity  from  the  coronal  lines.  In  this  way  otu-  can  jud^c 
as  to  the  reliability  of  the  latter.  If  it  is  im{K)ssihle  to  use  an  arc 
or  a  spark  comparison  spectrum,  the  stronger  iodine  absorption 
lines  or  the  narrow  strips  of  continuous  spectrum  between  them 
may  be  found  suitable  in  the  neighborhood  of  X  530^. 

Ralph  t.  DeLiry 

Dominion  .\stbunomic.\l  Ubservatory,  Orr\w\ 
April  1, 1918 


